How are eyes examined in the developing nations?

Eye examinations are conducted the same way as in the US. The Snellen Eye Chart is the chart most commonly used by ophthalmologists and optometrists to measure a person's distance visual acuity. The chart is used to measure how well you can see at a standing or seated distance of 20 feet or 6 meters away from the chart. (20 feet equals approximately 6 meters)

For example, if the eye doctor tells you your distance visual acuity is 20/20 (feet) or 6/6 (meters) this is determined to be 'normal' vision. However if your distance visual acuity is measured at 20/200 or 6/60, this means you can see at a distance of 20 feet/6 meters what a person with normal vision can see at 200 feet/60 meters. If you are told your measurement is 20/400 or 3/60 this means you can only see the big "E" on the eye chart, whereas a person with normal vision would be able to see this at 400 feet.

Optometrist, Dr. Wendy Strouse Watt, provides a clear and expanded explanation of How Visual Acuity is Measuredon the Macular Degeneration Support website.

The following chart produced by the World Health Organization's Programme for Prevention of Blindness shows the different categories of vision impairment:

CATEGORIES OF VISUAL IMPAIRMENT

Category of Visual Impairment

Visual Acuity with BEST POSSIBLE Correction

Maximum less than:

Minimum equal to or better than:

1

6/18
3/10 (0.3)
20/70

6/60
1/10 (0.1)
20/200

2

6/60
1/10 (0.1)
20/200

3/60
1/20 (0.05)
20/400

3

3/60
1/20 (0.05)
20/400

1/60 (finger-counting at 1 metre)
1/50 (0.02)
5/300 (12/1200)

4

1/60 (finger-counting at 1 metre)
1/50 (0.02)
5/300 (12/1200)

5

No light perception

9

Undetermined or unspecified

Adapted from International Statistical Classification of Diseases and Related Health Problems, Tenth Revision, Geneva, World Health Organization, 1992

Categories of visual impairment 1 and 2 are referred to as "low vision", categories 3, 4 and 5 as "blindness", and category 9 as "unqualified visual loss". If the extent of the visual field is taken into account, patients with a field no greater than 10? but greater than 5? around central fixation should be placed in category 3 and patients with a field no greater than 5? around central fixation should be placed in category 4, even if visual acuity is not impaired.